Supported options are fallback which provides a fallback node which will be used when $node is non-literal; and fallback_type either 'dec' or 'hex' which is used when parsing the fallback node,
or if $node is a plain literal.
(The actual datatype of the fallback node is ignored for hysterical raisins.)

Additionally,
any function from List::MoreUtils can be exported by request,
except true and false as they conflict with the constants above.